Since 1982 the U.S. Geological Survey (USGS) has collected a large amount of surficial and shallow subsurface geologic information in the deep parts of the Gulf of Mexico. These data include digital sidescan sonar imagery, digital seismic-reflection data, and descriptions and analyses of piston and gravity cores. The data were collected during several different projects that addressed surficial and shallow subsurface geologic processes. Some of these data sets have already been published, but the growing interest in the occurrence and distribution of gas hydrates in the Gulf of Mexico warrants integrating these existing data and associated interpretations into a GIS to provide regional background information for ongoing and future gas hydrate research.

Purpose:

This GIS data layer outlines the extent of the sidescan sonar image that was collected by the SeaMARC 1A system in 1990 in the eastern Gulf of Mexico on the Mississippi Fan.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19900325

Ending_Date: 19900408

Currentness_Reference: ground condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -86.544099

East_Bounding_Coordinate: -85.023094

North_Bounding_Coordinate: 26.817466

South_Bounding_Coordinate: 26.150872

Keywords:

Theme:

Theme_Keyword_Thesaurus: General

Theme_Keyword: U.S. Geological Survey

Theme_Keyword: USGS

Theme_Keyword: Woods Hole Science Center

Theme_Keyword: WHSC

Theme_Keyword: Coastal and Marine Geology Program

Theme_Keyword: CMGP

Theme_Keyword: Gulf of Mexico GIS database

Theme_Keyword: ArcView

Theme_Keyword: shapefile

Theme_Keyword: polygon

Theme_Keyword: Information Archives Field Activity 90001

Theme_Keyword: interpretation

Theme_Keyword: data coverage

Theme_Keyword: U.S. Exclusive Economic Zone

Theme_Keyword: EEZ

Theme:

Theme_Keyword_Thesaurus: ISO 19115 Topic Category

Theme_Keyword: oceans and estuaries

Theme_Keyword: geoscientificInformation

Place:

Place_Keyword_Thesaurus: General

Place_Keyword: Gulf of Mexico

Place_Keyword: Mississippi Fan

Place_Keyword: North America

Place_Keyword: United States

Access_Constraints: None

Use_Constraints:

Public domain data from the U.S. government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.

This image was used to trace the outline of the sidescan data coverage.

Process_Step:

Process_Description:

The SeaMARC 1A sidescan sonar mosaic was registered and displayed in ArcView. The extent of the SeaMARC1A sidescan coverage was then interactively drawn over the mosaic to create this ArcView GIS layer.

Source_Used_Citation_Abbreviation: seamarc.tif

Process_Date: Unknown

Source_Produced_Citation_Abbreviation: seamarc_coverage.shp

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: David Twichell

Contact_Organization: U.S. Geological Survey

Contact_Position: Oceanographer

Contact_Address:

Address_Type: mailing and physical address

Address: 384 Woods Hole Road

City: Woods Hole

State_or_Province: MA

Postal_Code: 02543-1598

Country: USA

Contact_Voice_Telephone: (508) 548-8700 x2266

Contact_Facsimile_Telephone: (508) 457-2310

Contact_Electronic_Mail_Address: dtwichell@usgs.gov

Process_Step:

Process_Description:

The projection of the shapefile was originally Geographic-NAD27, and it was changed to Geographic-WGS84 using the Project utility in ArcToolbox.

Source_Used_Citation_Abbreviation: seamarc_coverage.shp

Process_Date: 2005

Source_Produced_Citation_Abbreviation: seamarc_coverage_project.shp

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: David Twichell

Contact_Organization: U.S. Geological Survey

Contact_Position: Oceanographer

Contact_Address:

Address_Type: mailing and physical address

Address: 384 Woods Hole Road

City: Woods Hole

State_or_Province: MA

Postal_Code: 02543-1598

Country: USA

Contact_Voice_Telephone: (508) 548-8700 x2266

Contact_Facsimile_Telephone: (508) 457-2310

Contact_Electronic_Mail_Address: dtwichell@usgs.gov

Process_Step:

Process_Description: Dataset copied and renamed.

Source_Used_Citation_Abbreviation: seamarc_coverage_project.shp

Process_Date: 2005

Source_Produced_Citation_Abbreviation: seamarc_coverage.shp

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: David Twichell

Contact_Organization: U.S. Geological Survey

Contact_Position: Oceanographer

Contact_Address:

Address_Type: mailing and physical address

Address: 384 Woods Hole Road

City: Woods Hole

State_or_Province: MA

Postal_Code: 02543-1598

Country: USA

Contact_Voice_Telephone: (508) 548-8700 x2266

Contact_Facsimile_Telephone: (508) 457-2310

Contact_Electronic_Mail_Address: dtwichell@usgs.gov

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Vector

Point_and_Vector_Object_Information:

SDTS_Terms_Description:

SDTS_Point_and_Vector_Object_Type: G-polygon

Point_and_Vector_Object_Count: 1

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Geographic:

Latitude_Resolution: 0.000000

Longitude_Resolution: 0.000000

Geographic_Coordinate_Units: Decimal degrees

Geodetic_Model:

Horizontal_Datum_Name: D_WGS_1984

Ellipsoid_Name: WGS_1984

Semi-major_Axis: 6378137.000000

Denominator_of_Flattening_Ratio: 298.257224

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: seamarc_coverage

Entity_Type_Definition: Shapefile Attribute Table

Entity_Type_Definition_Source: ESRI

Attribute:

Attribute_Label: FID

Attribute_Definition: Internal feature number.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: Shape

Attribute_Definition: Feature geometry.

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: ID

Attribute_Definition:

an internal control parameter automatically created during processing

Attribute_Definition_Source: Software generated

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0

Range_Domain_Maximum: 0

Attribute_Units_of_Measure: integer count

Attribute_Measurement_Resolution: 1

Attribute:

Attribute_Label: AREA

Attribute_Definition: Area of survey coverage in square meters

Attribute_Definition_Source: USGS

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 3047305677.490

Range_Domain_Maximum: 3047305677.490

Attribute_Units_of_Measure: square meters

Attribute_Measurement_Resolution: .001

Attribute:

Attribute_Label: PERIMETER

Attribute_Definition: Length of perimeter of SeaMARC 1A coverage in meters

Attribute_Definition_Source: User defined

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 489205.081

Range_Domain_Maximum: 489205.081

Attribute_Units_of_Measure: meters

Attribute_Measurement_Resolution: .001

Distribution_Information:

Distributor:

Contact_Information:

Contact_Person_Primary:

Contact_Person: David Twichell

Contact_Organization: U.S. Geological Survey

Contact_Position: Oceanographer

Contact_Address:

Address_Type: mailing and physical address

Address: 384 Woods Hole Road

City: Woods Hole

State_or_Province: MA

Postal_Code: 02543-1598

Country: USA

Contact_Voice_Telephone: (508) 548-8700 x2266

Contact_Facsimile_Telephone: (508) 457-2310

Contact_Electronic_Mail_Address: dtwichell@usgs.gov

Resource_Description: Downloadable data.

Distribution_Liability:

Although this data set has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: SHP

Format_Version_Number: 3.3

Format_Specification: ESRI polygon shapefile

Format_Information_Content:

The SHP file contains the geospatial data. The SHX file contains the index of the geospatial data. The DBF file contains the attribute data in dBase format. The PRJ file contains the coordinate system information (optional). The AVL file contains the legend information (optional). The SBN and SBX files contain the spatial index of the geospatial data (optional). The XML file contains the metadata describing the data set <data set name>.shp.xml. An ASCII version of the metadata file. A browse graphic showing the data layer coverage and extent (optional).

The data are available in Environmental Systems Research Institute (ESRI) shapefile format. The user must have ArcGIS® or ArcView® 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of importing data. A free data viewer, arcexplorer, capable of displaying the data is available from ESRI at www.esri.com.